In a certain noisy factory, workers are provided with earplugs and are expected to wear them.

In a certain noisy factory, workers are provided with earplugs and are expected to wear them. An industrial hygienist inspecting the plant found that 100 of the 500 workers in the factory were not wearing their earplugs because they regarded them as uncomfortable and as a nuisance. When all the workers are given a hearing test, it was found that 16 of the earplug wearers and 40 of the non-wearers had developed significant hearing loss. All had had normal hearing at their pre- employment examinations 4 years earlier, when the plant opened. (Hint: State a hypothesis before you tackle this problem.)